July 18, 2015
Quality indicators in colonoscopy have been established and are here to stay.
Seth A. Gross, MD
Associate Professor of Medicine, NYU School of Medicine, Chief Gastroenterology – Tisch Hospital, NYU Langone Medical Center
This article appears in the June/July 2015 issue of AGA Perspectives.
Colonoscopy has been shown to detect both adenomatous polyps and colon cancer. However, studies have shown colon adenomas and colon cancer have been missed despite having colonoscopy. To reduce the miss rates during colonoscopy, rigorous quality metrics have been developed. Recently a multisociety quality guideline was released stressing the importance of key metrics: bowel preparation, adenoma detection rate (ADR), cecal intubation and withdrawal time. The ADR benchmarks have increased to 30 percent for men and 20 percent for women. A split-dose bowel preparation is recommended as well as a withdrawal time of no less than 6 minutes.1 In the last of couple of years, there has also been a parallel improvement in equipment to potentially improve inspection of the colon with the goal of reducing the miss rate of adenomatous polyps.
Currently, high-definition white light (HDWL) colonoscopy is a common feature in a new colonoscope, but has demonstrated a marginal benefit for improving ADR. Digital chromoendoscopy (NBI, iScan, FICE) have not shown a higher ADR when compared to HDWL. Today, newer technologies can be subdivided into either “optical enhancement” or “mechanical enhancement.” These enhancements aim to get better surface visualization of the proximal area of the colonic folds and colon blind spots, such as flexures. The standard view of a colonoscope can range anywhere from 140 to 180 degrees. Full spectrum endoscopy (FUSE) has a center image of 160 degrees with two additional side cameras increasing the filed of view to 330 degrees. A single randomized study showed a significant ADR increase of 71 percent along with a decreased adenoma miss rate 7 percent (FUSE) versus 41 percent (standard forward view).2 However, this is only a single study and more studies are needed to confirm this dramatic ADR advantage.
Newer technologies can be subdivided into either “optical enhancement” or “mechanical enhancement.”
Several years ago the third-eye retroscope was a camera-based catheter, which went down the working channel of the scope and would come out retroflexed to view proximal folds. The device has been redesigned in the form of a panoramic cap, which has two cameras on each side of the cap. When snapped onto the tip of the scope the field of view increases to about 330 degrees.
Mechanical colonoscope enhancements are either single-use caps or a permanently integrated balloon, which is reusable. Endocuff (EC) is a single-use cap with soft fingerlike projection allowing for temporary gripping of colonic folds revealing the proximal side. A recent study showed a 14.7 percent increase in ADR compared to traditional optical colonoscopy.3 EndoRing (ER) is a disposable cap with circular rings, and when engaged with colonic fold it can cause mechanical shortening to stretch the colon and to better visualize colonic folds. Randomized study compared ER to standard colonoscopy and demonstrated a reduction in the ADR miss rate compared to standard colonoscopy. Another form of mechanical enhancement is the G-EYE, which is available outside the U.S. The G-EYE is an integrated balloon colonoscopy, which has an inflated balloon at the tip used during withdrawal. The balloon stretches the colon allowing for flattening of colonic folds. A prospective randomized control trial showed a significant reduction in ADR miss rate for the G-EYE, 7.5 percent, compared to 44 percent with standard colonoscopy.4
Quality indicators in colonoscopy have been established and are here to stay. The formula to achieve a high-quality colonoscopy is composed of endoscopist’s technique with quality equipment (HDWL). The technological advances in this space are changing the face of colonoscopy as we know it. The routine use of either optical or mechanical enhancements will be better defined as more scientific data is published.
There are several unanswered questions:
- Is optical or mechanical colonoscopy enhancement a need for every endoscopist?
- Should these advances be used only by those with a below benchmark ADR?
- Which is a better, optical or mechanical improvement?
- Do the cost implications of these technologies lead to improved outcomes?
There is continued emphasis on improving an endoscopist’s batting average, which is their ADR. After the endoscopist has exhausted correcting adjustable factors, such as bowel preparation, withdrawal time and inspection technique, but is still not achieving high-quality exams, the hype of new colonoscopy technology may ultimately be helpful.
Dr. Gross is a speaker for MEDIVATORS Inc.
1. Rex DK, Schoenfeld PS, Cohen J, et al. Quality indicators for colonoscopy. Gastrointest Endosc. 2015 Jan;81(1):31-53.
2. Gralnek IM, Siersema PD, Halpern Z, et al. Standard forward-viewing colonoscopy versus full-spectrum endoscopy: an international, multicentre, randomised, tandem colonoscopy trial. Lancet Oncol 2014;15(3):353-60
3. Floer M, Biecker E, Fitzlaff R. et al. Higher adenoma detection rates with endocuff-assisted colonoscopy – a randomized controlled multicenter trial. PLoS One. 2014 Dec 3;9(12).
4. Halpern Z, Gross SA, Gralnek IM. Comparison of adenoma detection and miss rates between a novel balloon colonoscope and standard colonoscopy: a randomized tandem study. Endoscopy. 2015 Mar;47(3):238-44.